Free Radical Oxidative Stress Research Articles

Quercetin protects against ethanol-induced oxidative damage in rat primary hepatocytes

The pathogenesis and progression of alcoholic liver disease (ALD) are associated with free radical injury and oxidative stress, which could be partially attenuated by antioxidants and free radical scavengers. Quercetin, one of the most widely distributed flavonoids in plants, is a natural antioxidant. The hypothesis that quercetin could prevent the ethanol-induced oxidative damage in hepatocytes was investigated. The ethanol-intoxicated (100 mM for 8 h) rat primary hepatocytes were post-treated (2 h), simultaneously treated or pre-treated (2 h) with quercetin respectively, while the time-dependent (0.5–8 h) and dose-dependent (25–200 μM) quercetin pre-treatment were used in the present study. The parameters of lactate dehydrogenase (LDH), aspartate transaminase (AST), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were determined to address the alterations of cell damage and antioxidant state after quercetin intervention. The toxic insult of ethanol to hepatocytes was challenged by quercetin and these parameters almost returned to the level of control group when hepatocytes were pre-treated with quercetin at the dose of 50 μM for 2–4 h before ethanol exposure. In conclusion, quercetin pre-treatment provided protection against ethanol-induced oxidative stress in hepatocytes and may be used as a new natural drug for the prevention and/or treatment of ALD.

Aging Brain: Prevention of Oxidative Stress by Vitamin E and Exercise

With aging, the brain undergoes neuronal loss in many areas. Although the loss of cells in the cerebral cortex, in particular the frontal cortex, has been recognized with aging, the influence of synaptic losses has a larger impact on cognitive decline. Much of the recent research on animals, as well as humans, has been aimed at slowing the cognitive decline through enrichment, and it has been found that the key factors are antioxidants and exercise. Several reports support the concept that regular supplementation of vitamin E and physical activity from as early as middle age can slow the cognitive decline observed during the later years. A few studies have also suggested that exercise is analogous to acetylcholine esterase inhibitors that are also used extensively to treat cognitive impairment and dementia in Alzheimer's disease. In addition, reports also support that vitamin E and exercise may act synergistically to overcome free radical injury and oxidative stress in the aging brain.

Oxidative stress and inflammatory response in dermal toxicity of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWCNT) represent a novel material with unique electronic and mechanical properties. The extremely small size (∼1 nm diameter) renders their chemical and physical properties unique. A variety of different techniques are available for the production of SWCNT; however, the most common is via the disproportionation of gaseous carbon molecules supported on catalytic iron particles (high-pressure CO conversion, HiPCO). The physical nature of SWCNT may lead to dermal penetration following deposition on exposed skin. This dermal deposition provides a route of exposure which is important to consider when evaluating SWCNT toxicity. The dermal effects of SWCNT are largely unknown. We hypothesize that SWCNT may be toxic to the skin. We further hypothesize that SWCNT toxicity may be dependent upon the metal (particularly iron) content of SWCNT via the metal's ability to interact with the skin, initiate oxidative stress, and induce redox-sensitive transcription factors thereby affecting/leading to inflammation. To test this hypothesis, the effects of SWCNT were assessed both in vitro and in vivo using EpiDerm FT engineered skin, murine epidermal cells (JB6 P+), and immune-competent hairless SKH-1 mice. Engineered skin exposed to SWCNT showed increased epidermal thickness and accumulation and activation of dermal fibroblasts which resulted in increased collagen as well as release of pro-inflammatory cytokines. Exposure of JB6 P+ cells to unpurified SWCNT (30% iron) resulted in the production of ESR detectable hydroxyl radicals and caused a significant dose-dependent activation of AP-1. No significant changes in AP-1 activation were detected when partially purified SWCNT (0.23% iron) were introduced to the cells. However, NFκB was activated in a dose-dependent fashion by exposure to both unpurified and partially purified SWCNT. Topical exposure of SKH-1 mice (5 days, with daily doses of 40 μg/mouse, 80 μg/mouse, or 160 μg/mouse) to unpurified SWCNT caused oxidative stress, depletion of glutathione, oxidation of protein thiols and carbonyls, elevated myeloperoxidase activity, an increase of dermal cell numbers, and skin thickening resulting from the accumulation of polymorphonuclear leukocytes (PMNs) and mast cells. Altogether, these data indicated that topical exposure to unpurified SWCNT, induced free radical generation, oxidative stress, and inflammation, thus causing dermal toxicity.

Morphine and HIV‐Tat increase microglial‐free radical production and oxidative stress: possible role in cytokine regulation

Opiate abuse alters the progression of human immunodeficiency virus and may increase the risk of neuroAIDS. As neuroAIDS is associated with altered microglial reactivity, the combined effects of human immunodeficiency virus-Tat and morphine were determined in cultured microglia. Specifically, experiments determined the effects of Tat and morphine on microglial-free radical production and oxidative stress, and on cytokine release. Data show that combined Tat and morphine cause early and synergistic increases in reactive oxygen species, with concomitant increases in protein oxidation. Furthermore, combined Tat and morphine, but not Tat or morphine alone, cause reversible decreases in proteasome activity. The effects of morphine on free radical production and oxidative stress are prevented by pre-treatment with naloxone, illustrating the important role of opioid receptor activation in these phenomena. While Tat is well known to induce cytokine release from cultured microglia, morphine decreases Tat-induced release of the cytokines tumor necrosis factor-alpha and interleukin-6, as well as the chemokine monocyte chemoattractant protein-1 (MCP-1). Finally, experiments using the reversible proteasome inhibitor MG115 show that temporary, non-cytotoxic decreases in proteasome activity increase protein oxidation and decrease tumor necrosis factor-alpha, interleukin-6, and MCP-1 release from microglia. Taken together, these data suggest that oxidative stress and proteasome inhibition may be involved in the immunomodulatory properties of opioid receptor activation in microglia.

α-Tocopherol Protects Against Oxidative Stress in the Fragile X Knockout Mouse: an Experimental Therapeutic Approach for the Fmr1 Deficiency

Fragile X syndrome is the most common genetic cause of mental disability. The mechanisms underlying the pathogenesis remain unclear and specific treatments are still under development. Previous studies have proposed an abnormal hypothalamic-pituitary-adrenal axis and high cortisol levels are demonstrated in the fragile X patients. Additionally, we have previously described that NADPH-oxidase activation leads to oxidative stress in the brain, representing a pathological mechanism in the fragile X mouse model. Fmr1-knockout mice develop an altered free radical production, abnormal glutathione homeostasis, high lipid and protein oxidation, accompanied by stress-dependent behavioral abnormalities and pathological changes in the first months of postnatal life. Chronic pharmacological treatment with alpha-tocopherol reversed pathophysiological hallmarks including free radical overproduction, oxidative stress, Rac1 and alpha-PKC activation, macroorchidism, and also behavior and learning deficits. The restoration of the oxidative status in the fragile X mouse emerges as a new and promising approach for further therapeutic research in fragile X syndrome.

Polymorphism of glutathione S-transferases as genetic risk factors for the development of complications in type 2 diabetes mellitus

Background Diabetes is characterized by chronic hyperglycemia that produces dysregulation of cellular metabolism and result in excess free radical production and oxidative stress. Glutathione S-transferases (GSTs) are a family of multifunctional enzymes that work as antioxidants. Therefore, diminished expression of GSTs may result in a reduced body defense against oxidative stress, followed by development of diabetic complications. Objectives To investigate the possible association between GSTM1 and GSTT1 polymorphism and the occurrence of complications in type 2 DM and to study the other risk factors for complications in DM. Methods Twenty noncomplicated type 2 diabetic patients and 40 complicated type 2 diabetic patients were enrolled in the study. The GSTM1 and GSTT1 genotypes were identified by polymerase chain reaction of peripheral blood DNA samples. Analysis of data was done by using SPSS (SPSS, Chicago, Ill). Results The frequencies of null GSTM1 and GSTT1 genotypes were 55% (11/20) and 40% (8/20), respectively, in noncomplicated DM group. The frequencies of null GSTM1 and GSTT1 genotype in complicated DM group were 57.5% (23/40) and 60% (24/40), respectively. The null GSTT1 genotype was more prevalent in the group of complicated DM with odds ratio (odds ratio, 2.3; 95% confidence interval, 0.75-6.7) when compared with noncomplicated DM. Conclusion Our data provide evidence that diabetics with null GSTT1 genotypes are substantially at higher risk for developing complications.

Cytotoxicity of Nitroaromatic Explosives and their Biodegradation Products in Mice Splenocytes: Implications for their Immunotoxicity

Nitroaromatic explosives like 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenyl-N-methyl-nitramine (tetryl) comprise an important group of toxic environmental pollutants, whose toxicity is mainly attributed to the flavoenzyme electrontransferase-catalyzed redox cycling of their free radicals (oxidative stress) and DT-diaphorase [NAD(P)H:quinone oxidoreductase, NQO1, EC 1. 6.99.2]-catalyzed formation of alkylating nitroso and/or hydroxylamine metabolites. Because of the incomprehensive data on the immunotoxic effects of nitroaromatic explosives, we have studied the structure-cytotoxicity relationships in the action of tetryl, TNT as well as its amino and hydroxylamino metabolites, and related nitroaromatic compounds towards mouse splenocyte cells. The protective effects of desferrioxamine and the antioxidant N,N'-diphenyl-p-phenylene diamine against the cytotoxicity of TNT and other nitroaromatics showed that the oxidative stress-type cytotoxicity mechanism takes place. In addition, the cytotoxicity of nitroaromatics is also partly prevented by an inhibitor of NQO1, dicumarol. The cytotoxicity of the amino metabolites of TNT is also partly prevented by alpha-naphthoflavone and isoniazide, which points to the involvement of cytochromes P-450 in their activation. In general the cytotoxicity of nitroaromatics in splenocytes increases with an increase in their single-electron reduction potential, E1(7). This points to the prevailing mechanism of the oxidative stress-type cytotoxicity. The obtained structure-activity relationship and the studies of other mammalian cell lines showed that the immunotoxic potential of nitroaromatic explosives may decrease in the order tetryl > or = TNT > or = hydroxylamino metabolites of TNT > amino and diamino metabolites of TNT.

Antioxidant Status and Purine Bases in Carotid Artery Plaque

Free radical excess and oxidative stress are implicated in the formation and progression of atherosclerotic plaque through actions on susceptible vascular cells, such as by activating xanthine oxidase. Purine bases and other antioxidant compounds could play important protective roles in atherogenesis, as could nonenzymatic low molecular weight thiol defenses, not previously evaluated in carotid artery plaque. Therefore, we measured purine catabolites (hypoxanthine, xanthine, uric acid, allantoin) and antioxidant compounds (total sulphydryl groups, homocysteine, cysteine, and glutathione) in advanced carotid artery plaque and found a high ratio of allantoin to uric acid, suggesting a ongoing local oxidative stress.

Oleuropein as a bioactive constituent of functional milk and yogurt

In recent years, interest in antioxidants isolated from plants has arisen due to their vital role in the protection of cell damage caused by the excess of free radicals (oxidative stress) [1]. Moreover, antioxidants are also used by food industries, as additives for the improvement of several properties of foods (biofunctional foods). One of the most important and developing category in this area is the dairy products, which are natural sources of high nutritional value [2]. Oleuropein is an important constituent of olive fruits. According to in vivo and in vitro studies, oleuropein exhibits anti-ischemic, antioxidative, and hypolipidemic effects [2]. In the present study, two functional dairy products were prepared by addition of oleuropein. An analytical method for the measurement of oleuropein in milk and yogurt was developed and validated. The new products were examined about the stability of oleuropein during their treatment. The results showed that oleuropein was resistant during heating of milk at 90oC for 5min. Furthermore, during coagulation of milk, oleuropein was not hydrolysed by the produced acids, it was not metabolized by lactic acid bacteria and it did not stop their growth. Also its stability during the maintenance of milk and yogurt for 35 days at 4 oC was proven. The functional milk and yogurt production was performed in laboratory and semi-industrial scale. Oleuropein was completely soluble in the selected concentration (0.1mg/ml) and it did not give any peculiar taste, as the products had the same taste and flavor with the conventional ones [4]. The selection of the concentration was based on the oleuropein quantity corresponding to consumption of 15 olive drupes per day. All the above results show that oleuropein can be added as active ingredient in milk and yogurt and two new biofunctional products can be produced, whose properties remain constant, during the overall process.

Effect of Every Other Day Feeding on Mitochondrial Free Radical Production and Oxidative Stress in Mouse Liver

It is known that dietary restriction (DR) increases maximum longevity in rodents, but the mechanisms involved remain unknown. Among the possible mechanisms, several lines of evidence support the idea that decreases in mitochondrial oxidative stress and in insulin signaling are involved but it is not known if they are interconnected. It has been reported that when C57BL/6 mice are maintained on an every other day (EOD) feeding their overall food intake is only slightly decreased and plasma insulin-like growth factor (IGF)-1 is even somewhat increased. In spite of this, their maximum longevity is increased, analogously to what occurs in classic DR. Thus, this model dissociates the increase in longevity from the decrease in IGF-1 observed in classic DR. Based on these facts, we have studied the effect of EOD DR on the rate of mitochondrial reactive oxygen species (ROS) production, oxygen consumption, and the percent free radical leak (FRL) of well-coupled liver mitochondria, the marker of mtDNA oxidative damage 8-oxo-7,8-dihydro-2'deoxyguanosine (8-oxodG), the content of complexes I to IV of the respiratory chain, the apoptosis inducing factor (AIF), PGC1-alpha, UCP2, five different markers of oxidative damage to proteins and the full fatty acid composition on C57BL/6 mice liver. It was found that EOD DR decreased ROS production in complex I but not in complex III without changes in oxygen consumption. As a result, FRL was decreased in complex I. Oxidative damage to mtDNA (8-oxodG) and protein oxidation, glycoxidation and lipoxidation were also lower in the EOD restricted group in comparison with the control one while the degree of fatty acid unsaturation was held constant. The EOD group also showed decreases in AIF, PGC1-alpha, and UCP2. These results support the possibility that EOD DR increases maximum life span at least in part through decreases in mitochondrial oxidative stress which are independent from insulin/IGF-1-like signaling.

Evaluation of the preventative effects exerted byLactobacillus fermentumin an experimental model of septic shock induced in mice

The preventative effects of the probiotic Lactobacillus fermentum CECT5716 were evaluated in the lipopolysaccharide (LPS) model of septic shock in mice. The probiotic was administered suspended in drinking water at the final concentration of 108 colony-forming units/ml for 2 weeks before the induction of an endotoxic shock by an intraperitoneal injection of LPS (400 microg/200 microl per mouse). Blood and different organs were collected after 24 h to evaluate the severity of the endotoxic shock and the preventative effects of the probiotic. L. fermentum reduced TNF-alpha levels in blood, which promotes the major alterations observed during septic shock, as well as the infiltration of activated neutrophils into the lungs. Furthermore, free radical overproduction and oxidative stress were associated with a significant decrease in hepatic glutathione levels in septic mice, and with an excessive NO production attributed to the induction of the inducible isoform of NO synthase (iNOS). In fact, hepatic glutathione levels were significantly increased in the group of mice receiving the probiotic, and the increased iNOS expression both in the colon and lungs was down-regulated in those mice treated with L. fermentum. Finally, pre-treatment with L. fermentum may also exert its protective action modulating the expression of different cytokines in splenocyte-derived T cells such us IL-2, IL-5, IL-6 or IL-10. In conclusion, pre-treatment with L. fermentum may exert its protective action against LPS-induced organ damage in mice by a combination of several actions including its antioxidant properties and by reduction of the synthesis of the pro-inflammatory TNF-alpha and IL-6.

A systematic review of antioxidant treatment for amyotrophic lateral sclerosis/motor neuron disease

Free radical accumulation and oxidative stress have been proposed as contributing to the progression of amyotrophic lateral sclerosis (motor neuron disease). A range of antioxidant medications is available, and has been studied. We aimed to examine the effects of antioxidant medication in the treatment of people with amyotrophic lateral sclerosis, and searched the Cochrane Neuromuscular Disease Group Trials register (August 2005), MEDLINE (January 1966 to August 2005), EMBASE (January 1980 to August 2005) and other sources. Selection criteria were all randomized or quasi-randomized controlled trials of antioxidant treatment for amyotrophic lateral sclerosis. The authors independently applied the selection criteria, assessed study quality and two authors performed independent data extraction. The search identified 23 studies for consideration but only nine studies met the inclusion criteria. Only two studies used our predetermined primary outcome measure as the primary outcome measure (survival at 12 months treatment). However, sufficient data were available from four studies to allow analysis of this outcome measure, and a meta-analysis was performed. In the individual studies no significant effect was observed for vitamin E 500 mg twice daily; vitamin E 1 g five times daily; acetylcysteine 50 mg/kg daily subcutaneous infusion; or a combination of L-methionine 2 g, vitamin E 400 International Units, and selenium 0.03 mg three times daily (Alsemet). No significant effect on the primary outcome measure was observed in a meta analysis of all antioxidants combined. No significant differences were demonstrated in any of the secondary outcome measures. In the opinion of the reviewers, there is insufficient evidence of efficacy of individual antioxidants, or antioxidants in general, in the treatment of people with amyotrophic lateral sclerosis. One study reported a mild positive effect, but this was not supported by the analysis we used. Generally, the studies were poorly designed, and underpowered, with low numbers of participants and of short duration. Further well-designed trials of medications such as vitamin C and E are unlikely to be performed. If future trials of antioxidant medications are performed, careful attention should be given to sample size, outcome measures, and duration of the trial. The high tolerance and safety, and relatively low cost of vitamins C and E, and other considerations related to the lack of other effective treatments for amyotrophic lateral sclerosis, explain the continuing use of these vitamins by physicians and people with amyotrophic lateral sclerosis. While there is no substantial clinical trial evidence to support their clinical use, there is no clear contraindication.

Lipid peroxidation in women with epilepsy

Background:Lipid peroxidation is an indicator of free radical metabolism and oxidative stress in human beings and other organisms. Malondialdehyde (MDA), an end product of lipid peroxidation, is a metabolite that can be readily estimated in serum samples. Excess oxidative stress may be a final common pathway through which anti epileptic drugs may exert their teratogenic potential in pregnant women with epilepsy. Our objective in this study was to ascertain the variations in malondialdehyde (MDA) in women with epilepsy.Material and Methods:This study was carried out in the Kerala Registry of Epilepsy and pregnancy after obtaining clearance from the Institutional Ethics Committee. Informed consent was obtained from all the subjects. The quantitative examination of MDA was performed according to standard procedures. The ideal plasma level of MDA is below 2 nmol/ml.Results:Fifteen women with confirmed epilepsy (mean age 26.9 ± 3.5) were included in the study. Two women were pregnant. MDA levels ranged from 1.7 to 2.8 nmol/ml (mean level = 2.13 ± 0.37 nmol/ml). Eight women (53 %) had MDA levels above the upper limit of normal. Three patients had levels above 2.5 nmol/ml, which corresponded to the 75 centile.Conclusions:This study had shown that the estimation of MDA levels in plasma is a convenient method to study lipid peroxidation and thereby oxidative stress in women with epilepsy. Over half of Women With Epilepsy (WWE) have excess oxidative stress as indicated by high levels of MDA in the plasma. Correlations between MDA level and characteristics of epilepsy, AED therapy, nutritional status and other medical conditions need to be observed in a larger cohort.

急性感音難聴症例における酸化ストレス度の検討

One hundred thirty-two patients complaining of acute hearing loss or tinnitus were seen at the Department of Otolaryngology in Nippon Koukan Hospital and Koukan Clinic during the one-year period from April 2006 to March 2007. We investigated oxidative stress in 13 of 60 cases of acute sensorineural hearing loss (Group AHL) and 21 of 53 cases of chronic hearing loss, or tinnitus (Group CT). Free Radical Analytical System 4 (diacron-reactive oxygen metabolites) was used to investigate the level of free radical oxidative stress. We compared the d-ROM level between 13 Group AHL patients and 21 Group CT. The d-ROM levels were higher in Group AHL than in Group CT. We compared the d-ROM levels before treatment and after administration of glucocorticoids. After treatment, d-ROM levels decreased in Group AHL and hearing levels also improved. Some patients in Group CT underwent tinnitus retraining therapy (TRT) with a tinnitus control instrument (TCI) and were followed up. We conducted a survey to evaluate patients using the tinnitus handicap inventory (THI) score. Patients who underwent TRT were normal before therapy, but d-ROM levels did not indicate any change between before and after treatment although the THI scores improved significantly. Our findings suggest that acute Sensorineural hearing loss is related to oxidative stress at the onset of acute sensorineural hearing loss, such as sudden deafness.

Effect of 8.5% and 25% caloric restriction on mitochondrial free radical production and oxidative stress in rat liver

Previous studies have consistently shown that 40% caloric restriction (CR) decreases the rate of mitochondrial ROS production and steady-state levels of markers of oxidative damage to macromolecules including mitochondrial DNA. However, few investigations have studied whether these changes also occur in lower CR regimes. This is of potential interest since moderate levels of dietary restriction are more practicable for humans. In this investigation male Wistar rats were subjected to 8.5% and 25% caloric restriction. Neither 8.5% nor 25% CR changed mitochondrial ROS production, oxygen consumption or mtDNA oxidative damage in rat liver mitochondria. However, both 8.5% and 25% CR significantly decreased the five different markers of protein oxidation, glycoxidation and lipoxidation measured, aminoadipic and glutamic semialdehyde, carboxyethyl-lysine, carboxymethyl-lysine, and malondialdehyde-lysine. The fatty acid composition of liver mitochondria was also affected and led to a moderate decrease in the degree of membrane unsaturation in both 8.5% and 25% CR. While 8.5% CR only affected complex I concentration (which was decreased), 25% CR decreased complexes I and IV and increased complexes II and III of the respiratory chain. Apoptosis-inducing factor (AIF) significantly decreased in 25% CR but not in 8.5% CR. The results show that moderate levels of caloric restriction can have beneficial effects including decreases in oxidative protein modification and a lower sensitivity of membranes to lipid peroxidation, in association with a reprogramming of the respiratory chain complexes and AIF content.

Melatonin protects SK‐N‐SH neuroblastoma cells from amphetamine‐induced neurotoxicity

Several hypotheses regarding the mechanism underlying amphetamine-induced neurotoxicity have been proposed. One of them is based on the observation of free radical formation and oxidative stress produced by auto-oxidation of dopamine (DA). The formation of DA-related reactive oxygen species (ROS) such as superoxide and hydroxyl radicals appears to play an important role in amphetamine-induced neurotoxicity. Melatonin, the main secretory product of pineal gland, is well known for its protective effects that are currently attributed mainly to its radical scavenging and antioxidant properties. The present study was conducted to investigate the protective effects of melatonin on d-amphetamine (AMPH)-induced neurotoxicity in cultured human dopaminergic neuroblastoma SK-N-SH cells. Our data indicate that AMPH significantly reduces cell viability, induces oxidative stress (enhances ROS production and malondialdehyde levels), up-regulates alpha-synuclein expression and decreases intracellular ATP levels. However, pretreatment of SK-N-SH cells with melatonin prevents AMPH-induced loss of cell viability and induction of oxidative stress, while reducing alpha-synuclein expression and increasing ATP production. These results suggest that the antioxidant properties of melatonin may provide a protective mechanism against AMPH-induced neuronal degeneration.

Reactive oxygen species plasmatic levels in ischemic stroke

Oxidative stress is probably one of the mechanisms involved in neuronal damage induced by ischemia-reperfusion, and the antioxidant activity of plasma may be an important factor providing protection from neurological damage caused by stroke-associated oxidative stress. The aim of this study was to investigate the status of oxidative stress, NO and ONOO(-) levels in patients with atherothrombotic and lacunar acute ischemic stroke and iNOS, eNOS and nitrotyrosine expression in the same patients. Plasma ONOO(-) levels were significantly higher in patients than in controls while NO decreases in patients in respect to controls. Densitometric analysis of bands indicated that iNOS and N-Tyr protein levels were significantly higher in patients in respect to controls. This study has highlighted a significant NO decrease in our patients compared with controls and this is most probably due to the increased expression of inducible NO synthase by the effect of thrombotic attack. In fact, the constitutive NO isoforms, which produce small amounts of NO, are beneficial, while activation of the inducible isoform of NO, which produces much more NO, causes injury, being its toxicity greatly enhanced by generation of peroxynitrite. The significant ONOO(-) increase observed in our patients, compared to controls, is most probably due to reaction of NO with O(2)(*-) . These findings suggest that free radical production and oxidative stress in ischemic stroke might have a major role in the pathogenesis of ischemic brain injury. Peroxynitrite might be the main marker of brain damage and neurological impairment in acute ischemic stroke.

L‐NAME reverses quinolinic acid‐induced toxicity in rat corticostriatal slices: Involvement of src family kinases

Quinolinic acid (QA) is an endogenous excitotoxin acting on N-methyl-d-aspartate receptors (NMDARs) that leads to the pathologic and neurochemical features similar to those observed in Huntington's disease (HD). The mechanism of QA toxicity also involves free radicals formation and oxidative stress. NMDARs are particularly vulnerable to the action of reactive oxygen species (ROS) and reactive nitrogen species (RNS) that can act as modulators of the activity of protein tyrosine kinases (PTKs) and phosphotyrosine phosphatases (PTPs). Because QA is able to activate neuronal nitric oxide synthase (nNOS) as well as to stimulate the NMDARs, we evaluated the effect of Nomega-Nitro-l-arginine-methyl ester (l-NAME), a selective nNOS inhibitor, on QA-induced neurotoxicity in rat corticostriatal slices. In electrophysiologic experiments we observed that slice perfusion with QA induced a strong reduction of field potential (FP) amplitude, followed by a partial recovery at the end of the QA washout. In the presence of l-NAME the recovery of FP amplitude was significantly increased with respect to QA alone. In synaptosomes, prepared from corticostriatal slices after the electrophysiologic recordings, we observed that l-NAME pre-incubation reversed the QA-mediated inhibitory effects on protein tyrosine phosphorylation pattern, c-src, lyn, and fyn kinase activities and tyrosine phosphorylation of NMDAR subunit NR2B, whereas the PTP activity was not recovered in the presence of l-NAME. These findings suggest that NO plays a key role in the molecular mechanisms of QA-mediated excitotoxicity in experimental model of HD.

Antioxidant treatment for amyotrophic lateral sclerosis or motor neuron disease

Free radical accumulation and oxidative stress have been proposed as contributing to the progression of amyotrophic lateral sclerosis (or motor neuron disease). A range of antioxidant medications are available, and have been studied. To examine the effects of antioxidant medication in the treatment of people with amyotrophic lateral sclerosis. We searched the Cochrane Neuromuscular Disease Group Trials register (August 2005), MEDLINE (from January 1966 to August 2005), EMBASE (from January 1980 to August 2005) and other sources. All randomized or quasi-randomized controlled trials of antioxidant treatment for amyotrophic lateral sclerosis. The authors independently applied the selection criteria, assessed study quality and two authors performed independent data extraction. The search identified 23 studies for consideration but only nine studies met the inclusion criteria. Only two studies used our predetermined primary outcome measure as the primary outcome measure, (survival at 12 months treatment). However, sufficient data were available from four studies to allow analysis of this outcome measure, and a meta-analysis was performed. In the individual studies no significant effect was observed for vitamin E 500 mg twice daily; vitamin E 1 g five times daily; acetylcysteine 50 mg/kg daily subcutaneous infusion; or a combination of L-methionine 2 g, vitamin E 400 International Units, and selenium 3 x 10-5g three times daily (Alsemet). No significant effect on the primary outcome measure was observed in a meta-analysis of all antioxidants combined. No significant differences were demonstrated in any of the secondary outcome measures. There is insufficient evidence of efficacy of individual antioxidants, or antioxidants in general, in the treatment of people with amyotrophic lateral sclerosis. One study reported a mild positive effect, but this was not supported by the analysis we used. Generally the studies were poorly designed, and underpowered, with low numbers of participants and of short duration. Further well-designed trials of medications such as vitamin C and E are unlikely to be performed. If future trials of antioxidant medications are performed, careful attention should be given to sample size, outcome measures, and duration of the trial. The high tolerance and safety, and relatively low cost of vitamins C and E, and other considerations related to the lack of other effective treatments for amyotrophic lateral sclerosis, explain the continuing use of these vitamins by physicians and people with amyotrophic lateral sclerosis. While there is no substantial clinical trial evidence to support their clinical use, there is no clear contraindication.

Oxidative and nitrosative stress in acute ischaemic stroke

Increased nitric oxide (NO) production may result in further brain damage via nitric oxide synthase uncoupling in patients with acute ischaemic stroke by increasing free radical formation and oxidative stress. In this connection, we measured nitrite and nitrate (NO metabolites), ischaemia-modified albumin (IMA) and thiobarbituric acid-reactive substances (TBARS) in patients with ischaemic stroke. We studied 41 patients with ischaemic stroke (22 men and 19 women, aged 65+/-13 years) and 37 age- and sex-matched controls (22 men and 15 women, aged 65+/-8 years). Blood samples were drawn within the first 24 h from the onset of symptoms in the patient group. Fasting morning samples were used in the control group. Concentrations of nitrite and nitrate were determined by Griess reagent; concentrations of IMA were determined by the albumin cobalt-binding test; and concentrations of TBARS were determined colorimetrically by thiobarbituric acid. Nitrate, IMA and TBARS concentrations were significantly increased compared with controls (P<0.005, P<0.001, and P=0.01, respectively). Patients with acute ischaemic stroke exhibit abnormalities in a range of markers of increased nitrosative and oxidative stress. These abnormalities may contribute to greater brain damage in patients with acute ischaemic stress.